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Behringer Studio Processors

There's not a MIDI socket in sight on this range of German studio units. They are simply good solid audio processors. Dave Lockwood checks them out.

Behringer may currently be among the lesser known names in the field of effects and processors in the UK, but their units look set to rapidly gain a reputation for providing not only excellent performance, but also offering good value for money. The company, which is based in West Germany, is apparently the brainchild of one Ulrich Behringer, an engineer who initially took to designing and building his own units out of dissatisfaction with other people's!

At present, the Behringer range consists primarily of basic studio processing 'tools' - compressor, gates, EQ, dynamic filter etc, although the first unit to be designed was, in fact, their exciter. All the devices share the same 1U 19" rack-mount design, with fairly conventional cosmetics - black, with red and gold legending. Having spent more years than I care to think of peering at racks full of black fascias in dimly lit control rooms, I have arrived at the very firm conclusion that light coloured front panels with dark legending are significantly easier on the eye, and thereby more efficient over a long period of time. This is, however, purely a personal opinion and doubtless others, Behringer among them, would allege that black is best, but as far as I know nobody has ever properly researched the subject.

The units on test include the Professional Exciter Type F, Professional Denoiser MkII, and Multiband Expander Gate, with a multichannel stereo headphone amp thrown in for good measure. The Denoiser, apart from being titled with the worst 'non-word' of the year so far, is a single-ended noise reduction device working on the dynamic filter principle employed by Symetrix, dbx, et al. The three processor devices supplied for review were equipped with electronically balanced (transformer balancing optional) XLR connections (20kOhm impedance), without parallel jacks, although I believe jacks are available instead of the XLRs as an option, at suitably reduced cost. Noise and distortion figures are exemplary - 0.03% THD @ 1 kHz, and dynamic range typically in excess of 102dB. Frequency response is reckoned to be maintained within 1/2dB from 10Hz to 20kHz. Mains input is via the normal IEC socket, with mains lead supplied, complete with moulded-on plug. I actually received three leads with moulded-on USA two-pin plugs and only one with a proper UK three-pin, but I hope it would be the distributor's intention to supply them in this country complete with the requisite connector - I'm sure everybody is as sick as I am of hacking off inappropriate moulded plugs on supplied mains leads!


Most recording people are familiar enough by now with the general principle of the 'Aural Exciter' (an Aphex trademark), although when the devices first appeared in the latter half of the Seventies, the technique was so shrouded in mystery that you weren't allowed to buy the units, only hire them, and clients were actually charged by the 'processed minute' for the use of the system! It seems hard to believe now just what hype surrounded the original unit from Aphex, the inventors of the technique - I remember being told by a sales rep that it was "a secret process involving the addition of psychoacoustic clues, above the normal range of human hearing"! The truth was much simpler, of course - the technique used was harmonic synthesis, creating artificial top-end by controlled distortion, and like most other techniques it has developed over the years, although the principle remains the same.

In essence, a sidechain signal is filtered to remove everything below the upper midrange, and then fed into a stage that generates primarily even-order harmonic distortion. A controlled amount of this signal is then fed back into the main signal path, and as even-order harmonics have 'musical' intervals (octave, fifth, etc), the synthesized top-end appears to bear some relationship to, and therefore readily becomes a plausible part of, the original signal. Because the additional harmonics are all pitched higher than the original signal, the subjective effect is one of 'brightening' the output. Things gets a bit more sophisticated than that in practice, for compression is normally employed in the sidechain and sometimes some creative phase effects at the output, but that is essentially how it works.


Behringer's Professional Exciter bears a remarkably close operational and visual resemblance to the ubiquitous Type C Aphex unit, with just Drive, Tune, and Mix controls for the operator to play with. The two channels share a common In/Out switch (all the switches are two-colour self-indicating, mechanical latching types), but there are individual Solo switches for each side, and each channel has its own tri-colour process monitor LED.

To anyone who has ever used a device of this type at all, operating the Behringer will be simplicity itself - to anyone who hasn't, a few words of explanation will suffice. The Drive control sets the level into the sidechain, monitored by the LED. A rear panel switch, labelled 'Line/Mic Instr' can be used for course level matching, according to whereabouts in your system you have the unit patched (two-position internal slide switches give a choice of operating levels). Conventionally, Exciters are either used on channel insert points, or patched across main outputs, feeds to recorders, power amps, etc. Using them on an auxiliary send/ return loop is a bit more tricky, as many exciters' controls do not allow for the complete removal of the original signal, and returning a mix of straight and processed output makes it very difficult to balance the effect properly. But with the Behringer unit you can use the Solo facility, if you really want to use it in this way. Each channel has its own Solo switch, which can be used to monitor just the output of the harmonic generator stage, which is most helpful when setting the Tune control to the area you want, and keeps you fully aware of exactly what you are adding to your signal.


It is an unfortunate fact of life that all 'harmonic generator' type exciters (as opposed to the simpler adaptive EQ variety) are terribly level dependent in operation. The setting of the Drive knob determines how much signal the harmonics stage receives, whilst the Mix control governs how much of the additional signal reaches the output. This inevitably means that the two controls interact to a large degree - setting up an exciter always seems to become a balancing act between these two! Too little Drive and you get no discernible effect at all, whilst too much produces a noticeably distorted output - increasing the Drive level usually means you have to back off on the Mix, etc. The Behringer exciter seems a little less critical in this area than some units, perhaps indicating some enhancements in the design of the sidechain. But what that might consist of, I am unable to speculate as I received very sparse documentation, and all of that still in German - English manuals will be available to accompany production units, however!

The Tune control, like the controls on all the units, consists of a fine resolution click-stop pot (for no particular operational reason that I can discern), entirely devoid of front panel calibration markings - this is certainly an encouragement to rely on your ears! Personally, I would have liked to see some actual frequencies marked, but I suppose I would have to concede their virtual irrelevance to most users, most of the time.

With the Behringer, as indeed with all exciters, the rule has to be to tune as high as you can possibly get away with, unless you are searching for a special effect. Tuning too low into the midrange can produce a very harsh and 'peaky' effect, which can be great for a really brash snare drum, say, but will spell disaster for anything more transparent and subtle in character. When processing a whole mix, or trying to achieve the much sought after intimate 'breathy' vocal sound, the Tune control definitely needs to stay near the top of its range. Subjectively, the Tune control on this unit seems to have a little more scope than many other devices, extending both lower into the midrange and higher at the very top. Alternatively, the design is simply more efficient at harmonic generation, in which case I have successfully been tricked into thinking there is a wider range to play with - either way, it works very well, and is fairly easy to set up.

"Behringer's Professional Exciter bears a remarkably close operational and visual resemblance to the ubiquitous Type C Aphex unit..."


I have never seen an article about exciters that didn't warn against over-use, and it is indeed all too easy to spoil the effect by overdoing it. The ear adjusts so rapidly to hearing a flattering enhanced top-end, that you soon start to think that the device isn't really doing much and succumb to the temptation to add just a touch more. This, invariably, has detrimental consequences, usually only discovered the day after!

The exciter is not really an 'effect', it is a studio tool that should be thought of in a similar fashion to compressors and expanders. I regard it as primarily a corrective process, for recovering lost or absent top-end information. Pleasing though an 'enhanced' breathy vocal is, it does not beat a 'real' breathy vocal, or a really clean recording of any sort which has all its natural top-end intact. Compared with the real thing, an 'enhanced' sound is always 'harsher' and ultimately fatiguing - the danger is that with the easy option of an enhancer lying there just waiting to be patched in, too many people never find out what the real thing sounds like!

Using them after the original recording stage, however - for tape copying, production mastering, etc - is a different story, for enhancers excel at compensating for copying losses, or overcoming the bandwidth restrictions of different media. The greatest danger when 'copy compensating' is always the inevitability of raising the noise floor while enhancing the wanted parts of the spectrum, and many people find the optimum setup for this process is actually an enhancer/exciter followed by a dynamic filter, such as Behringer's Denoiser. This pair make a very powerful and effective combination indeed, not only for copying, but also for squeezing the maximum quality out of limited bandwidth, or noisy samples or effects.

Within the constraints of my preferred usages, the Behringer Type F Professional Exciter performed very well indeed, and I would make no criticism of it from an operational point of view whatsoever. My reservations are on the usage of exciters in general, and certainly not specific to this unit. I was very interested to note that the Behringer system is actually updatable - apparently the main processing chip can be removed and replaced with a newer version if and when Behringer come up with something better! Full marks for that - could this set a trend for other hardware manufacturers previously untouched by this trait of the software market? Another plus point for Behringer is their five year warranty, faithfully supported by the UK distributor Ampsound, I understand - that too sets a standard that should help overcome the usual reluctance to buy from a less well known company. All in all this is a very solid product indeed, at an attractive price.


I am impressed by the performance of this unit, too. In fact, it bears a remarkably close resemblance to my all-time favourite gate, which set new standards for audio integrity and speed - the Aphex 612. The control layout is identical, the spec pretty much the same, but above all the audio performance is in the same state-of-the-art league. I don't think this is likely to be mere coincidence, so I am inclined to wonder if there is some tie-up between the companies that nobody is going out of their way to advertise. Either way, it results in an excellent product for the end user.

The Behringer unit offers Hi and Lo filters in the sidechain for frequency conscious gating, which helps avoid false triggering by narrowing down the signal fed to the detection circuitry to just the relevant part of the sound spectrum. The Lo Cut control sweeps from 30Hz to 3kHz, and the Hi Cut from 150Hz to 15kHz - the filters are quite steep (12dB/Octave), and used in tandem are able to be very selective. Threshold is adjustable from -50 to +20dBm, to determine the onset of processing, with a Range control setting the amount of attenuation (0 to 100dB). The envelope controls, Attack, Hold, and Release, all function pretty much as you would expect, although the fastest attack time of 3ms is worthy of special mention - the only other unit I know that can do this is, of course, the Aphex 612! This lets the gate open extremely fast so that very little of the all-important leading edge of the waveform gets lost, resulting in a subjectively cleaner sound.

As with any gate, the combination of a very fast attack and a high threshold setting will produce audible clicks as the waveform of the signal is modified, but within the confines of common sense this Behringer gate is remarkably free of audible vices. The Hold time (10ms-4sec), a function not available on all types of gate, delays the onset of the release phase, preventing 'hunting' when a fast release is used and facilitating more accurate tracking of difficult signal dynamics. Release has plenty of scope, variable from 40ms to 4sec. The final control, Ratio, determines the VCA slope, and thus enables the unit to function as an expander as well as a gate, variable from 20:1 (gating) all the way up to 1:1.


The Expander Gate has five switches per channel, each with associated status LED - Process In/Out, Filter In/Out, External Keying, Key Listen, and Duck. Channel 2 has an additional Slave switch, causing it to track channel 1's characteristic for stereo operation. Key Listen lets you hear the effect of the filters in the sidechain, which makes them much easier to set up; you simply have to tune the two cut-off points until you are left only with the bit that you want to pass through the gate, enormously enhancing selectivity.

"...the Behringer Type F Professional Exciter performed very well indeed, and I would make no criticism of it from an operational point of view whatsoever."

The Key inputs, via ¼" jacks on the rear panel, allow an external signal to control the gating action, such as for tightening grouped backing vocals or instruments, where one part is used as the master and all the others made to follow its dynamics. A related function is the Ducking facility, which causes gain reduction under the control of an external source. This can be very effectively employed in a high energy mix, when you want a certain part to dominate and yet you have little headroom left for it to be added on top of what is already there. The lead vocal track is often used to 'dip' the backing guitars in rock tracks and, provided it is not overdone, it can add to rather than detract from the sense of power in the mix.

The expander action can be visually monitored via a three LED display - red for below threshold, green for above, and yellow for the Hold phase. I particularly appreciate the fact that the display still works when the gate is not switched in. This can, where necessary, facilitate setting up by eye, before introducing the process into a signal path that is already active - either as an afterthought, or as a 'rescue job'!


The Behringer gates are very quiet and very fast. Like all quality gates, the unit is very good at doing nothing. Which is to say that when there is a signal present above the selected threshold, then that signal is passed as if the processor was not there. Side-effects of even heavy gating are usually minimal, and the softer expansion slopes perform in exemplary fashion. The click-stop pots are very pleasant and contribute to the general feeling of this being a quality instrument. Some might criticise the sparsity of control calibration, although in this particular application that does not bother me. Verdict? An exemplary unit of its type.


The big advantage of single-ended noise reduction units is that, unlike encode/decode processes such as Dolby or dbx, they can tackle source noise - ie. noise present as part of the original signal, not just that introduced by a transmission medium such as tape or line noise. They rely on the 'masking' principle, where noise cannot be heard when a reasonable level of signal is present, and it is only as the signal level drops that it is necessary to apply processing. Fortunately, this mirrors the situation in the natural world where louder sounds tend to have more HF energy, or quieter ones less, if you prefer, and consequently some quite severe HF roll-off can often be tolerated, provided it is dynamically related to level.

Some units of this type employ a dynamic filter in combination with an expander, which completely shuts down the signal path below a preset threshold. Others, like the Behringer unit, use only the dynamic filter stage, which means that on material with really wide-band noise (perhaps hum as well as hiss) some noise will remain even with the filter fully activated.


The Denoiser's dynamic filter is of the fixed slope, variable frequency variety - quite a gentle slope in fact, 6dB/Octave minimising unwanted filter effects (phase anomalies, resonance, etc). There are no front panel markings for the filter threshold control, just Min and Max, but it sounds like 20kHz down to about 400Hz, ie. pretty low down the spectrum. There is just a single Threshold control and In/Out switch for the user to play with - the amount of top-end removed being determined by how far below the threshold level the signal drops.

Envelope functions are entirely automatic, and seemingly programme determined, for the unit is very low on unwanted effects, noise tails, pumping etc - whatever you try to catch it out with. It is also very fast, for there is minimal blurring of transients if the amount of processing is kept to a reasonable level. If the source signal is not desperately noisy to start with, then some dramatically quiet results can be achieved. Whereas with a real salvage job, it becomes a matter of achieving the best compromise between noise reduction and the effects on the wanted part of the spectrum.

A 10-segment LED meter is provided, which gives quite a good impression of the action of the filter, and although this too is entirely uncalibrated, it does help to some extent in setting up the unit.

"Each of the Behringer devices is characterised by being no more complicated than it needs to be, and therefore gets the job done with the minimum of fuss."

Fade-outs were handled very sympathetically, although these are often a problem area for the dynamic filter, and in general the unit excelled in displaying a very gentle touch on the kind of non-transient signals that are notoriously difficult to gate without creating side-effects, such as vocals. A dynamic filter can be much more forgiving than an expander on sounds with a slow decay, provided the target area is primarily high frequency.


It is perhaps a sign of the times that most people's first thoughts for the use of a dynamic filter such as the Denoiser no longer revolve around tape machines, although I can confirm it performs perfectly well in this area. It is really excellent at cleaning up samples, unobtrusively getting rid of any hiss, quantisation noise, multiplexed output noise, etc. The combination of Exciter and Denoiser is outstanding here, producing results that you would find hard to believe could come from a 12-bit sampler. It can make quite a difference also to synths, particularly the first generation FM variety, although the difficulty for those people who never put synths on tape any more is that you would certainly need a few more than just two channels to play with. Fortunately, Behringer also make the Denoiser in an eight channel version, using the same DNR processing chip, and with an identical complement of controls. Like the Type F Exciter, the DNR chip at the heart of the Denoiser is said to be updatable, should Behringer (or anyone else?) develop something that could do the job better.

One final application. Have you ever soloed all your mixer's effects returns on a big mix? The combined 'quiescent' racket of perhaps half a dozen digital units is enough to rob any mix of a certain amount of clarity and transparency, and being able to gently roll-off the top-end when nothing much is happening makes all the difference. That's the beauty of the Behringer Denoiser: you can usually just stick it in circuit, dial up the setting and forget about it - and there are not too many devices you can say that about!


Behringer make a fine range of units, built to a high standard, with toroidal transformers in the gate and headphone amp, classically neat interboard connection by socketed ribbon cables in the one multi-board design (the Expander Gate), properly mounted connectors that place no stress on the PCBs etc, and with an audio performance to match. The 'value for money' factor, plus the upgrade possibilities and the extended warranty, should help overcome the inevitable suspicion that confronts a new name in any field. Each of the Behringer devices is characterised by being no more complicated than it needs to be, and therefore gets the job done with the minimum of fuss. Indeed, on a unit such as the Denoiser, the user is given virtually nothing to set up (and therefore has nothing to go wrong) - an attribute which will appeal to the professional every bit as much as the inexperienced user! There is no programmability, no multi function switches, no memories, just good solid audio processing - and not a MIDI socket in sight!


All prices inc VAT.
Pro Exciter Type F £322.
2 channel Pro Denoiser £281.75.
Pro Headphone Amplifier £391.
Multiband Expander/Gate £793.50.

Ampsound, (Contact Details).


Behringer's 'Professional Headphone Amplifier' provides three independent stereo headphone amps in a 1U rack chassis, with all the connectors, front and rear, being ¼" jacks. Each amplifier can pick up on either its own individual (rear) pair of inputs, or a common stereo bus, which is available to all three. Stereo/Mono switching is available on each 'module' to ensure that if there is only one input, such as a mono desk foldback send, the signal can still appear in both earpieces, and there are Left and Right Mute switches to defeat either half of a stereo source, where necessary.

The routing options contrive to offer the maximum flexibility without becoming over-complicated. The Left/Right bus, which has an alternative input on the front panel (single stereo jack), is governed by two master level controls with associated 'signal present' LEDs. The pots seem to function as input attenuators, not output controls, which means you will generate tons of distortion if these are wide open, even though the headphone controls may be at a sensible listening level. I expected the LEDs to be bi-colour, and to act also as 'clip' indicators, but they unfortunately do not.

The unit is very loud and very clean, with a feeling of plenty of power in reserve. It was entirely happy with all the headphone types I could throw at it, and was also untroubled by a decently long cable run. Background noise is very low - something I find extremely important in reducing stress and fatigue when headphones may have to be worn for a long continuous period, such as for location recording monitoring. Indeed, I would really have appreciated this unit a few years ago, when I was regularly doing 'live' location recordings, as it allows entirely independent listening levels and source selection for up to three people.

The standard of construction is every bit as high as that of the other units described, and indeed matches the standard of performance. The unit is rugged, and seems well protected against any form of abuse, electronic or physical, that it is likely to encounter. This is an unglamorous task, performed well - what more could you ask of a headphone amp?

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Recording Techniques

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Prism 16-Track PC Sequencer

Sound On Sound - Copyright: SOS Publications Ltd.
The contents of this magazine are re-published here with the kind permission of SOS Publications Ltd.


Sound On Sound - Jul 1990

Review by Dave Lockwood

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> Recording Techniques

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